In an Orthogonal Frequency-Division Multiple Access (OFDMA) system, interference power often varies in frequency and time due to frequency and time selective fading. Interference power also varies due to frequency and time domain power adaptation. It is important for an OFDMA system design to utilize variations in the interference power to maximize system performance. Accordingly, an efficient mechanism to facilitate interference power estimation is necessary.
Normally, interference power is estimated based on the measured channel characteristics of either the pilot channels or the data channels. This estimation is often coupled with channel estimation or data channel detection, which requires a complicated receiver design, and often leads to unsatisfactory results. In an OFDMA system such as a 3GPP LTE system, this problem is exacerbated because the reference signals are only located in a few OFDMA symbols. Therefore, if all base stations are synchronized, the reference signals can collide with one another in some OFMDA symbols while there are no reference signals in other OFMDA symbols. Accordingly, the interference power estimation based on reference signals can be much higher than the actual interference power experienced by the data channel in a lightly loaded system, which may result in pessimistic channel quality indicator (CQI) reporting and poor system performance.
Therefore, there is a need in the art for an improved system and method for estimating interference power. In particular, there is a need for an interference power estimation technique that takes advantage of the dynamic nature of an OFDMA system.